Foundation of the empire

At the beginning of the 3rd century ad, the Arsacid empire had been in existence for some 400 years. Its strength had been undermined, however, by repeated Roman invasions, and the empire became once more divided, this time between Vologeses VI (or V), who seems to have ruled at Ctesiphon, on the left bank of the middle Tigris in what is now Iraq, and Artabanus V, who was in control of Iran and whose authority at Susa, in southwestern Iran, is attested by an inscription from 215. (See alsoMesopotamia, history of: The Sāsānian period.)

It was against Artabanus V that a challenger arose in Persis. Ardashīr I, son of Pāpak and a descendant of Sāsān, was the ruler of one of the several small states into which Persia had gradually been divided. His father had taken possession of the city and district of Istakhr (Estakhr), which had replaced the old residence city of Persepolis, a mass of ruins after its destruction by Alexander the Great in 330 bc. Pāpak was succeeded by his eldest son, who was soon killed in an accident, and in ad 208 Ardashīr replaced his brother. He first built for himself a stronghold at Gūr, named, for its founder, Ardashīr-Khwarrah (“Ardashīr’s Glory”), now Fīrūzābād, southeast of Shīrāz in Fārs. He subdued the neighbouring rulers and in the process disposed of his own remaining brothers. His seizure of such areas as Kermān, Eṣfahān, Elymais, and Mesene—to the east, north, and west of Fārs, respectively—led to war with Artabanus, his suzerain. The conflict between the two rivals lasted several years, during which time the Parthian forces were defeated in three battles. In the last of these, the battle on the plain of Hormizdagān (224), Artabanus was killed.

There is evidence to support the assumption that Ardashīr’s rise to power suffered several setbacks. Vologeses VI (or V) struck coins at Seleucia on the Tigris as late as ad 228/229 (the Seleucid year 539). Another Parthian prince, Artavasdes, a son of Artabanus V, known from coins on which he is portrayed with the distinguishing feature of a forked beard, seems to have exercised practical independence even after 228. Numismatic evidence further reflects the stages of Ardashīr’s struggle for undisputed leadership. He appears on his coins with four different types of crowns: as king of Fārs, as claimant to the throne before the battle at Hormizdagān, and as emperor with two distinctly different crowns. It has been suggested that this evidence points to two separate coronation ceremonies of Ardashīr as sovereign ruler, the second perhaps indicating that he may have lost the throne temporarily.

According to al-Ṭabarī, the Muslim historian (9th–10th century), Ardashīr, after having secured his position as a ruler in western Iran, embarked on an extensive military campaign in the east (227) and conquered Sakastan (modern Sīstān), Hyrcania (Gorgān), Margiana (Merv), Bactria (Balkh), and Chorasmia (Khwārezm). The inference that this campaign resulted in the defeat of the powerful Kushān empire is supported by the further statement of al-Ṭabarī that the king of the Kushān was among the eastern sovereigns, including the rulers of Tūrān (Quzdar, south of modern Quetta) and of Mokrān (Makran), whose surrender was received by Ardashīr. These military and political successes were further extended by Ardashīr when he took possession of the palace at Ctesiphon and assumed the title “king of kings of the Iranians” and, across the Tigris River, when he refounded and rebuilt the city of Seleucia under the new name Veh-Ardashīr, the “Good Deed of Ardashīr.”

The chronology of events in the early Sāsānian period was calculated by the German Orientalist Theodor Nöldeke in 1879, and his system of dating is still generally accepted. The discovery of fresh evidence in manuscript materials dealing with the life of Mani, a religious leader whose activities fall in the early Sāsānian period, led to a reassessment of Nöldeke’s calculations by another German, Walter Bruno Henning, by which the principal events are dated about two years earlier. Another alternative was proposed by the Iranian scholar Sayyid Hasan Taqizadeh, who preferred a sequence by which the same events are placed about six months later than the dates established by Nöldeke. Since the dating systems employed by the Sāsānians themselves were based on the regnal years of the individual kings, whose exact coronation dates are often subject to disputation, several details remain uncertain, and their definite solution has not been possible. A firmer basis of calculation is obtained when the ancient sources quote dates in terms of the Seleucid era, either according to the computation that prevailed in Babylonia, which started from 311 bc, or after the Syrian reckoning, beginning in 312 bc. See the table for dates of events of the early Sāsānian period as they can be established on direct numismatic or literary evidence in the differing chronological systems of Nöldeke, Henning, and Taqizadeh. The table of reign dates of the kings is based mainly on Nöldeke’s system.

Shortly before his death, probably because of failing health, Ardashīr abdicated the throne in favour of his chosen heir, his son Shāpūr I. The latter assumed the responsibilities of government but delayed his coronation until after his father’s death. Coins thus exist showing Ardashīr together with his son as heir apparent and Shāpūr alone wearing the eagle cap, indicating the exercise of royal rule before his coronation—besides the normal series showing Shāpūr crowned as king.

The Sāsānian empire at the time of Shāpūr I.Encyclopædia Britannica, Inc.

Shortly after his accession, Shāpūr was faced with an invasion of Persia by the emperor Gordian III (reigned 238–244):

The emperor Gordian levied in all of the Roman empire an army of Goths and Germans and marched against Asūristān [Iraq], the empire of Iran and us. On the border of Asūristān, at Massice [Misikhe on the Euphrates], a great battle took place. The emperor Gordian was killed and we destroyed the Roman army. The Romans proclaimed Philip [the Arabian; reigned 244–249] emperor. The emperor Philip came to terms, and as ransom for their lives he gave us 500,000 dinars and became our tributary. For that reason, we renamed Massice Fīrūz-Shāpūr [“Victorious (Is) Shāpūr”].

Several years later, in 256 (or 252), another confrontation between the Persians and Romans occurred:

We attacked the Roman empire and we destroyed an army of 60,000 men at Barbalissus [in Syria]. Syria and its surrounding areas we burned, devastated and plundered. In this one campaign we captured of the Roman empire 37 cities,

including Antioch, the capital of Syria, itself. A third encounter took place when the emperor Valerian came to the rescue of the city of Edessa, Syria (modern Urfa, Turkey), which was besieged by the Persian army:

He [Valerian] had with him [troops from] Germania, Rhaetia…[follow the names of some 29 Roman provinces], a force of 70,000 men. Beyond Carrhae and Edessa there was a great battle between the emperor Valerian and us. We made the emperor Valerian prisoner with our own hands; and the commanders of that army, the praefectus praetorii, senators and officers, we made them all prisoner, and we transported them to Persia. We burned, devastated and plundered Cilicia and Cappadocia…[follow the names of 36 cities].

The source for these quotations is Shāpūr’s own account of the events. It was unknown until 1938, when expeditions sponsored by the Oriental Institute of the University of Chicago discovered a long inscription on the walls of an Achaemenian building known as the Kaʿbe-ye Zardusht (“Kaaba of Zoroaster”). The text is in three languages, Sāsānian Pahlavi (Middle Persian), Parthian, and Greek. Besides the narrative of the military operations, the inscription provides a description of the Persian empire of the time and an inventory of the Zoroastrian religious foundations established by Shāpūr to commemorate his victorious wars. These foundations were fire temples dedicated to the “soul” (memory) of the founder himself, members of the royal family, and prominent officials who had served under Shāpūr and his predecessor. The list of the officials, who are specified by the positions they held, throws light on the administrative organization of the empire.

Organization of the empire

In contrast to his father, who claimed to be “king of kings of Iran” (shāhanshāh īrān), Shāpūr I assumed the title “king of kings of Iran and non-Iran” (shāhanshāh īrān ud anīrān). This formula was retained by his successors as the regular designation of the Sāsānian emperors. The hereditary local dynasties, which under the Arsacids had ruled many of the most important provinces, were to a large extent abolished. Instead, such areas as Maishān (Mesene), in western Iran, and Sakastan (Sīstān), in eastern Iran, were now ruled by members of the Sāsānian family, who were appointed by the sovereign with the title of shāh (king). Among such provincial governors, precedence was often given to the heir to the throne, who was placed in control of large territories, such as the former Kushān empire (Kūshānshahr) and Armenia, and given the title “great king” (wuzurg shāh). This arrangement lasted until the early 4th century ad, and such emperors as Shāpūr I and Hormizd II are known to have first held the title kūshānshāh as governors of the areas of Bactria, Sogdiana, and Gandhāra. Next in the hierarchy came the few remaining hereditary vassals, such as the kings of Iberia (now Georgia) in the Caucasus, and the chief nobles of the empire, among whom the Warāz, Sūrēn, and Karēn families retained their prominent position from Parthian times. Next in line were the satraps, whose importance had diminished and who were now no more than the administrators of larger cities or court officials.

The list of provinces given in the inscription of Kaʿbe-ye Zardusht defines the extent of the empire under Shāpūr, in clockwise geographic enumeration: (1) Persis (Fārs), (2) Parthia, (3) Susiana (Khūzestān), (4) Maishān (Mesene), (5) Asūristān (southern Mesopotamia), (6) Adiabene, (7) Arabistān (northern Mesopotamia), (8) Atropatene (Azerbaijan), (9) Armenia, (10) Iberia (Georgia), (11) Machelonia, (12) Albania (eastern Caucasus), (13) Balāsagān up to the Caucasus Mountains and the Gate of Albania (also known as Gate of the Alans), (14) Patishkhwagar (all of the Elburz Mountains), (15) Media, (16) Hyrcania (Gorgān), (17) Margiana (Merv), (18) Aria, (19) Abarshahr, (20) Carmania (Kermān), (21) Sakastan (Sīstān), (22) Tūrān, (23) Mokrān (Makran), (24) Paratān (Paradene), (25) India (probably restricted to the Indus River delta area), (26) Kūshānshahr, until as far as Peshāwar and until Kashgar and (the borders of) Sogdiana and Tashkent, and (27), on the farther side of the sea, Mazun (Oman). This empire, considerably more extensive than that controlled by the Arsacid dynasty, was governed by members of the royal family and by appointed officials directly responsible to the throne. The greater degree of centralization thus attained by the Sāsānian government partly explains its increased military effectiveness in comparison with the Arsacid administration. Tight organization of the numerous central and provincial officials, whose ranks in the bureaucratic structure on different levels were strictly defined, also contributed toward general administrative efficiency.

Another trend that developed in the Sāsānian period, although it had already made itself felt under the Arsacids, was a strict principle of dynastic legitimacy. For a usurper not of the royal blood to come to the throne was an extremely rare occurrence, though it was in fact accomplished by Bahrām VI Chūbīn in 590. Loyalty was given, however, to the whole royal house, rather as it was in the later Ottoman Empire. The person of the individual ruler was a matter of comparatively lesser importance, and one member of the dynasty could readily be removed and replaced by another. In accordance with this principle of legitimacy, Persian tradition carried the Sāsānian line back to the Achaemenids and, ultimately, to the kings of the legendary period.

Religious developments

The ancestors of Ardashīr had played a leading role in the rites of the fire temple at Istakhr, known as Ādur-Anāhīd, the Anāhīd Fire. With the new dynasty having these priestly antecedents, it seems only natural that there would have been important developments in the Zoroastrian religion during the Sāsānian period. In fact, the evolution of Zoroastrianism as an organized religion into something resembling its modern form can be regarded as having begun in this period. Under the Parthians, local magi (priests) had no doubt continued to perform the traditional ceremonies associated with the old Iranian deities, the fire cult, the creed preached by Zoroaster, with its emphasis on the worship of Ahura Mazdā, and even the cults of cosmopolitan deities that were introduced in the Hellenistic period and later.

Under the Sāsānians, stress was increasingly placed on the fire cult and the worship of Ahura Mazdā. Strong mutual relationships, furthermore, were developed between religion and the state, and an ecclesiastical organization was set up in which every local district of any importance had its own mobed (“priest”; originally magupat, “chief priest”). At their head stood the mobedān mobed (“priest of priests”), who, in addition to his purely religious jurisdiction, appears, especially in later times, to have had a more or less decisive voice in the choice of a successor to the throne and in other matters of state. There is also some evidence that the mobeds, by virtue of their proficiency in reading and writing in general and in the interpretation of the sacred scriptures in particular, performed the duties of registrars and scribes in semireligious or nonreligious matters, like the Christian clergy in medieval Europe. This situation in turn makes it likely that the priestly library buildings not only contained the sacred texts, charters, and other church records but also served as repositories of local archives, title deeds, and other documents of a legal nature. The building known as Kaʿbe-ye Zardusht and referred to as a bun-khānag (“foundation house”) may well have served this very purpose.

In the matter of religious practice, the theology of the Sāsānians appears to have developed from that of their home province of Persis. There, extraneous religious influences were limited. The opposition between the good spirit of light and the demons—between Ahura Mazdā (Ormizd) and Angra Mainyu (Ahriman)—remained the essential dogma. All the other gods and angels were restricted to the role of subordinate servants of Ahura Mazdā, whose highest manifestation on earth was not so much the sun or the sun godMithra (Mihr) but rather the holy fire guarded and attended by his priests. At the same time, the names of such deities as Verethraghna (Wahrām), Mithra, and Anāhitā (Anāhīd) were still associated with the names of fire temples or classes of fires. Divine names were also used to designate the 30 days of each month and of the 12 months of the year, plus five epact days, called gahānīg, to align the lunar with the solar year.

All the prescriptions of purity were scrupulously observed. The elaborate ritual still maintained in modern times by the Parsi for the purification and custody of the sacred fire was no doubt observed under the Sāsānians. The officiating priest was girt with a sword and carried in his hand the barsman (barsom), or bundle of sacred grass. His mouth was covered to prevent the sacred fire from being polluted by his breath. The practice of animal sacrifice, abhorred by the modern followers of Zoroaster, is attested for the Sāsānian period at least as late as the reign of Yazdegerd I (399–420). On the days of the important festivals, such as Nōgrūz (Nōrūz), the first day of the vernal equinox, and on the day of Mihragan (the 16th day of the seventh month), the sacred fire was displayed to the faithful (wehden) at nightfall from some vantage point. Under the Sāsānians the injunction not to pollute the earth by contact with corpses but to expose the dead on mountaintops to vultures and dogs was strictly observed. Ahura Mazdā preserved his character as a national god who bestowed victory and world dominion on his worshipers. In rock-relief sculptures he appears on horseback as a god of war.

Theology was further developed, and an attempt was made to modify the old dualistic concept by considering both Ahura Mazdā and Angra Mainyu as emanations of an original principle of infinite time (Zurvān). This doctrine enjoyed a certain degree of official recognition in early Sāsānian times. In the reign of Khosrow I (531–579), however, the “sect of the Zurvānites” was declared to be heretical. The chief trend of Sāsānian religion, apart from the process of being institutionalized, was toward elaborating its ritual and doctrine of purity. A complete and detailed system of casuistry was developed, which dealt with all things allowed and forbidden and with the forms of pollution and the expiation of each. One of the consequences of this development was that increasing emphasis was placed on orthodoxy and rigorous obedience to priestly injunctions. Nonorthodox and heretical cults and forbidden manners and customs came to be regarded as a pollution of the land and a serious offense to the true God. It was the duty of the believer to combat and destroy the unbelievers and the heretics. In short, the tolerance of the Achaemenids and the indifference of the Arsacids were gradually replaced by religious intolerance and persecution.

Despite his priestly family origin, Ardashīr himself seems not to have been the person responsible for initiating these new directions in religious affairs. It was once believed that the institutionalization of the Zoroastrian church and the codification of its scriptures and beliefs were the work of a high priest named Tansar, a contemporary of Ardashīr I, of whose activities an account is preserved in the Letter of Tansar, contained in the History of Ṭabaristān (Tārīkh-e Ṭabaristān) by the Persian writer Ibn Isfandiyār (flourished 12th–13th century). New inscriptional evidence, however, suggests that, if Tansar was, in fact, a historical personage, his role in religious matters was overshadowed by Kartēr (Karder). The latter, an ehrpat (or herbed, “master of learning”) and mobed (or magupat, “priest”) already prominent under Shāpūr I, appeared during the reigns of Bahrām I (reigned 273–276) and Bahrām II (276–293) as the dominant figure in the Zoroastrian church. As stated in the Kaʿbe-ye Zardusht inscription of Kartēr, he claims credit for suppressing non-Zoroastrian religious communities in Iran (“and Jews, Buddhists, Brahmans, ‘Nazoreans,’ Christians…were struck upon”), imposing orthodoxy and discipline on the priesthood (“the heretics [ahlomog]…who in the Magus estate did not attend to the Mazdean religion and the services to the gods with discrimination, I struck them with punishment and I castigated them”), and establishing royal foundations for the maintenance of priests and of sacred fires. (See alsoZoroastrianism.)

The reference in the Kartēr inscription to two sects of Christians continues the indications from Syriac sources that Christianity had by that time (the second half of the 3rd century) gained a firm footing in the lands of the Tigris and the Euphrates, where it was strongest among the Aramaic-speaking communities. Ultimately, Christian missionary effort came to expand over the whole of Iran and even beyond. As long as the Roman Empire remained pagan, the Christian communities of Iran lived undisturbed by persecution, while the Christians themselves showed outspoken hostility toward such heterodox sects as the Manichaeans and the Gnostic followers of Marcion (the Marcionites) and Bardesanes, who existed side by side with them. Once the emperor Constantine I (the Great; reigned 306–337) made Christianity the official religion of the Roman world, the Iranian Christians were drawn to feel a certain sympathy for their foreign coreligionists, and political significance came to be attached by the Sāsānian rulers to these religious connections with an often hostile foreign power. After 339 the Christians of Iran were subjected to severe persecutions at the hands of Shāpūr II and his successors. Nonetheless, substantial Christian communities survived in parts of Iran long after the end of the Sāsānian dynasty.

During the reign of Shāpūr I a new religious leader and movement made their appearance. Mani (216?–274?) was the offspring of a Parthian family resident in Babylonia (“a thankful disciple I am, risen from Babel’s land”) but was himself a speaker of Aramaic. Knowledge of his teachings was greatly increased by the discovery in the early 20th century of many fragments of Manichaean literature in eastern Turkistan. Subsequently a large part of the Kephalaia, a collection of the religious injunctions of Mani, was recovered in a Coptic version found in Egypt. These texts can now be collated with the versions of Manichaean doctrines as reported by the Church Fathers, including St. Augustine. From this cumulative documentation, to which other sources can be added, it appears, among other things, that Mani’s teachings were formulated under the strong influence of Gnostic ideas and philosophy. Mani proclaimed himself to be the last and greatest Apostle of Jesus as well as the Paraclete announced in the Gospel According to John. With the Gnostic interpretation of the Gospel, Mani tried to combine the doctrines of Zoroaster and Jesus in order to create a new religion of a universal character. There is a tradition that he made his first appearance as a teacher on the coronation day of Shāpūr (April 12, 240, or April 9, 243), but other evidence suggests that Mani was not necessarily in Iran at the time and may have been on a sea journey to India when he started preaching. He later returned and found many followers, among whom were Fīrūz (Pērōz) and Mihrshāh, governor of Maishān (Mesene), both brothers of Shāpūr. Even the king himself is said to have been impressed and to have granted the prophet several personal interviews. On the last such occasion, Mani presented the king with his first book, the Shāpuragān (Shabuhragan), a summary of his teachings (“dedicated to Shāpūr”) written in the Middle Persian language, which provides further evidence of a degree of royal favour. During Shāpūr’s reign the religion of Mani was thus propagated in and beyond Iran. The heir to the throne, Hormizd I, was also favourably disposed toward him. Shāpūr’s younger son, Bahrām I, however, yielded to pressure from the priestly establishment, and Mani was executed. After that, Manichaeism was persecuted and destroyed in Iran. Yet it maintained itself not only in the West, penetrating far into the Roman Empire, but also in the East, in Khorāsān and beyond the boundaries of the Sāsānian empire. There the seat of its leader was at Samarkand, whence it penetrated Central Asia.

Art and literature

Perhaps the most characteristic and certainly among the most impressive relics of Sāsānian art are the great rock sculptures carved on the limestone cliffs that are found in many parts of the country. The best-known groups are at Naqsh-e Rostam and Naqsh-e Rajab, both near Persepolis, and at Bishāpūr, an ancient city a few miles north of Kāzerūn in Fārs. At Fīrūzābād—the ancient Gūr, also in Fārs—are two reliefs of Ardashīr I, one depicting the overthrow of Artabanus V, the other depicting an investiture scene. Not far away, in the valley at Sar Mashhad, a representation of Bahrām II shows that king in the process of slaying two lions. At Dārābgerd, about 180 miles (290 km) southwest of Shīrāz, Shāpūr I is shown triumphing over three Roman emperors—Gordian III, Philip the Arabian, and Valerian. At Naqsh-e Bahrām, north of Kāzerūn, Bahrām III is depicted enthroned. The same ruler appears at Qaṣr-e Abū Nasr, near Shīrāz, and at Gūyom, not far from there. Sāsānian sculptured reliefs are less numerous outside Fārs, but a Sāsānian equestrian that once existed at Rayy (ancient Rhagae), southeast of modern Tehrān, was replaced in the 19th century by a representation of Fatḥ ʿAlī Shāh, a member of the then-ruling Qājār dynasty. At Salmās, near Lake Urmia, Ardashīr I is shown on horseback while receiving the surrender of a Parthian personage. There are also later Sāsānian sculptures at Ṭāq-e Bostān, near Kermānshāh, showing Ardashīr II, Shāpūr III, and Khosrow II. In many of these representations the Sāsānian kings can be identified by their individual crowns.

The most ambitious and celebrated architectural achievement of the dynasty is the vast palace at Ctesiphon, built by Khosrow II (590; 591–628), a part of which is still standing. It is known as the Ṭāq Kisrā and is notable for its great barrel vault in baked brick, a typically Sāsānian architectonic device. Many Sāsānian buildings can also be seen in Fārs, where the characteristic construction is of limestone blocks embedded in strong mortar. The most important of these are near Shīrāz: the palace of Ardashīr I to the south at Fīrūzābād and a small, well-preserved palace at Sarvestān, southeast of Shīrāz, in which the rooms are roofed with domes and squinches, features often found in Sāsānian architecture. Excavations at Bishāpūr, or Shāhpūr, have revealed some mosaic floors and other features of this important Sāsānian town. Numerous fire temples of the period survive, especially in Fārs; these are square buildings roofed by a dome over four arches. Sāsānian remains of considerable extent also exist at Qaṣr-e Shīrīn, on the road from Baghdad to Tehrān, and at Gondēshāpūr, modern Shāhābād, south of Dezfūl.

Generally speaking, the Sāsānian era was one of a renaissance in Iranian art, which, if not quite on the same level as the Achaemenian achievement, was of no small importance. Metalwork reached a high level of artistry and craftsmanship; its most characteristic decorative themes are hunting scenes portraying the Sāsānian kings in action. A gold and enamel drinking vessel (now in the Bibliothèque Nationale in Paris) from the time of Khosrow I—known as the Cup of Solomon and, according to one tradition, a gift from the caliph Hārūn al-Rashīd to Charlemagne—is perhaps the most sumptuous specimen of Sāsānian metalworking. The art of gem engraving produced many fine intaglio stamp seals and cameos. The coins invariably bear a Pahlavi inscription; on the obverse (seephotograph) is the head of the king, wearing his characteristic crown, accompanied by his name and title, while on the reverse is the fire altar with its guardians and a legend such as “Fire of Ardashīr” or “Fire of Shāpūr” or, in the later period, an abbreviated mint name and the regnal date. (For additional discussion of Sāsānian visual arts, seeart and architecture, Iranian.)

Khosrow II, coin, ad 590–628; in the collection of the American Numismatic Society.Courtesy of the American Numismatic Society

The acquaintance with Greek language and literature maintained by the Arsacid court had begun to decline during the last century of that dynasty. Greek versions nonetheless accompany the Parthian and Middle Persian texts of the inscriptions of Ardashīr I and Shāpūr I, as in the case of the Kaʿbe-ye Zardusht inscription. Later inscriptions, however, are only in Parthian and Middle Persian, as in the case of the inscription of Narses at Paikuli.

Most of the comparatively few remaining examples of literature in Book Pahlavi—a form of Middle Persian somewhat different from that used in the Sāsānian inscriptions—is of late or post-Sāsānian date in its actual form, if not in content. This is partly due to the fact that the transition from an oral to a written literary tradition (both religious and secular compositions) took place in the latter part of the Sāsānian era. A passage in a religious text states that “it is proper to consider the living spoken word more weighty than the written.” It should be added that most Sāsānian literary remains are primarily of religious and historical rather than of literary interest. Just as foreign learning appears in religious works, likewise foreign prose works of entertainment came to Persia, where they were translated; among them, in the time of Khosrow I, were Hellenistic romance literature and Indian books of tales, such as Kalīlag and Dimnag, based on the Indian Pañca-tantra, or the legends of Barlaam and Josaphat (Balauhar and Budasaf).

Foreign policy

In foreign policy the issues under the Sāsānian kings remained, as of old, the defense and, when possible, the expansion of the eastern and western frontiers. The successful military campaigns in the eastern areas by Ardashīr I and Shāpūr I, which resulted in the annexation of the western part of the Kushān empire, have already been mentioned.

Conflicts with Rome

In the west the old contest for northern Mesopotamia—with the fortified cities of Carrhae, Nisibis, and Edessa—continued. The Sāsānians were all the more eager to regain and retain control of Armenia because there the Arsacid dynasty still survived and turned for protection to Rome, with which, in consequence, new wars continually broke out. In the reign of Bahrām II (276–293), the Roman emperor Carus (282–283) invaded Mesopotamia without meeting opposition and reached Ctesiphon. His sudden death, however, caused the Roman army to withdraw. Bahrām II had been prevented from meeting the Roman challenge by the rebellion of his brother, the kūshānshāh Hormizd, who tried to establish an independent eastern empire. This attempt ended in failure, however, and Bahrām II appointed his younger son, the future Bahrām III, as viceroy of Sakastan (Sīstān). After Bahrām II died, Narses, the youngest son of Shāpūr I, contested the succession of Bahrām III and won the crown. In memory of his victory, Narses erected a tower at Paikuli, in the mountains west of the upper Diyālā River, which was discovered in 1843 by the British Orientalist Sir Henry Rawlinson. Decorated with busts of Narses, the monument has a long inscription in Parthian and Middle Persian that tells the story of the events. In 296 Narses was forced to conclude a peace treaty with the Romans by which Armenia remained under Roman suzerainty and certain areas in northern Mesopotamia were ceded to Rome. By this treaty, which lasted for 40 years, the Sāsānians withdrew completely from the disputed districts. The Roman Empire had meanwhile become Christian, and the Syro-Christian populations of Mesopotamia and Babylonia began to feel sympathy with Roman policies for religious reasons. Christianity also became predominant in Armenia after its king adopted the Christian faith in 294. The Sāsānian emperors consequently felt the need to consolidate their Zoroastrianism, and efforts were made to perfect and enforce state orthodoxy. All heresy was proscribed by the state, defection from the official faith was made a capital crime, and persecution of the heterodox, the Christians in particular, began. Competition between Iran and Rome-Byzantium thus took on a religious dimension.

A new war was inevitable. It was begun by Shāpūr II in 337, the year of the death of Constantine I. Shāpūr besieged the fortress city of Nisibis three times without success. The emperor Constantius II (reigned 337–361) conducted the war weakly, but Shāpūr was distracted by the appearance of a new enemy, the nomadic Chionites, on his eastern frontier. After a long campaign against them (353–358), he returned to Mesopotamia and, with the help of Chionite auxiliaries, captured the city of Amida (modern Diyarbakır, Turkey) on the upper Tigris, an episode vividly narrated by the Roman historian Ammianus Marcellinus (c. 330–395). The emperor Julian the Apostate (361–363) reopened hostilities after the death of Constantius but died after having reached the vicinity of Ctesiphon. His successor, Jovian (363–364), was forced to give up the Roman possessions on the Tigris, including Nisibis, and to abandon Armenia and his Arsacid protégé, Arsaces III, to the Persians. The greater part of Armenia then became a Persian province.

Intermittent conflicts from Yazdegerd I to Khosrow I

After about two decades of disturbed reigns (Ardashīr II, Shāpūr III, Bahrām IV), Yazdegerd I came to the throne in 399. His reign is viewed differently by Christian and Zoroastrian sources. The former praise his clemency; the latter refer to him as “Yazdegerd the Sinful.” His initial inclination toward tolerance of Christianity and Judaism was met by resistance on the part of the nobility. Because of their attitude and because of the growing fanaticism of the Christians, Yazdegerd was forced to turn to repression. After his death (420) the nobles refused to admit any of Yazdegerd’s sons to the throne. But one of them, Bahrām, had the support of al-Mundhir, Arab king of Al-Ḥīrah (east of the lower Euphrates) and a Sāsānian vassal, and also, apparently, of Mihr-Narseh, chief minister in Yazdegerd’s last years, who was retained in office, and Bahrām eventually won the throne. As King Bahrām V (420–438), surnamed Gūr (for the onager, or wild ass), he became the favourite of Persian popular tradition, which exuberantly celebrates his prowess in hunting and in love. Unsuccessful in war with Byzantium (421–422), Bahrām V made a 100-year peace and granted freedom of worship to the Christians. In the east he did succeed in repelling an invasion by the Hephthalites. In the following decades, however (the second half of the 5th century), Hephthalite attacks continued to harass and weaken the Sāsānians. Fīrūz (reigned 457–484) fell in battle against them; his treasures and family were captured, and the country was devastated. His brother Balāsh (484–488), unable to cope with continuing incursions, was deposed and blinded. The crown fell to Kavadh (Qobād) I, son of Fīrūz. While the empire continued to suffer distress, he was dethroned and imprisoned (496), but he escaped to the Hephthalites and was restored (499) with their assistance. The Nestorian doctrine (claiming that divine and human persons remained separate in the incarnate Christ) had by then become dominant among the Christians in Iran and was definitely established as the accepted form of Christianity in the Sāsānian empire.

Kavadh I proved himself a vigorous ruler. He restored peace and order in the land. Amida was destroyed during his campaign against the Romans in 502, but another inroad by the Hephthalites in the east compelled him to ratify a peace treaty with the Byzantines. Toward the end of his reign, in 527, he resumed the war and defeated the Byzantine general Belisarius at Callinicum (531) with the support of al-Mundhir II of Al-Ḥīrah. Earlier in his reign he had moved away from the Zoroastrian church and favoured Mazdakism, a new socioreligious movement that had found support among the people. The crown prince, Khosrow, however, was an orthodox Zoroastrian; toward the end of his father’s reign, in collaboration with the chief mobed, he contrived to condemn the Mazdakites, who were destroyed in a great massacre in 528. On his father’s death, after acceding as Khosrow I (531–579), he concluded peace with the Byzantine emperor Justinian (532). He reestablished Zoroastrian orthodoxy, and, although some persecution of Christian communities occurred during periods of tension with Byzantium, the restoration of peace brought about a considerable amount of religious tolerance.

Khosrow I was one of the most illustrious Sāsānian monarchs. From his time dates a new and more equitable adjustment of the imperial tax system. The levying of land revenue in kind was replaced by a fixed assessment in cash, and these assessments continued in force later under the Arab administration. His reputation as an enlightened and just ruler was high during his lifetime and later became legendary. When Justinian I closed the philosophy school in Athens in 529, the last Neoplatonists turned to Khosrow in hopes of finding in him the true philosopher-king. Although they were disillusioned by conditions at his court, their gratitude was great when Khosrow obtained for them the right to return to Athens. From 540 onward Khosrow had been conducting a long war against Justinian, which, although interrupted by several armistices, lasted until the so-called 50 years’ peace of 561. Khosrow also extended his power to the Black Sea and inflicted heavy defeats on the Hephthalites. These military successes resulted partly because the armed forces and the chain of command were reorganized several times during Khosrow’s long reign.

Conflicts with the Turks and Byzantium

About 560 a new nation, that of the Turks, had emerged in the east. By concluding an alliance with a Turkish leader called Sinjibu (Silzibul), Khosrow was able to inflict a decisive defeat on the Hephthalites, after which event a common frontier between the Turkish and Sāsānian empires was established. Inevitably, this alliance became a source of possible friction, and the Turks sometimes acted as an ally of Byzantium against Iran in a second war (572–579).

Khosrow bequeathed this war to his son Hormizd IV (579–590), who, in spite of repeated negotiations, failed to reestablish peace between Byzantium and Iran, and fighting occurred intermittently throughout his reign. Hormizd was unable to display the same authority as his father, and he antagonized the Zoroastrian clergy by failing to take action against the Christians. He finally fell victim to a conspiracy headed by the general Bahrām Chūbīn. Hormizd’s son, Khosrow II, was set up against his father and forced to acquiesce when Hormizd was executed. New unrest broke out, in which Bahrām Chūbīn—though not of royal lineage—attempted to secure the throne. Simultaneously another pretender, Prince Bestām, decided to try his luck. Khosrow fled to Byzantium, and the emperor Maurice undertook to restore him by military force. Bahrām Chūbīn was routed (591) and fled to and was killed by the Turks, and Khosrow again ascended the throne in Ctesiphon. Bestām held out in Media until 596.

During the two reigns (590 and 591–628) of Khosrow II—surnamed Parvīz (the “Victorious”)—the Sāsānids achieved unprecedented splendour and material wealth. The assassination of Maurice (602) impelled Khosrow to war against Byzantium, in the course of which his armies penetrated as far as Chalcedon (opposite Constantinople), ravaged Syria, and captured Antioch (611), Damascus (613), and Jerusalem (614); in 619 Egypt was occupied. The Byzantine Empire was, indeed, at its lowest ebb.

It took the great emperor Heraclius, who was crowned in 610, many years to rebuild the nucleus of a new army. This done, however, he set out in 622 and retaliated vigorously against the Persians, whose armies were defeated everywhere. In 624 Heraclius invaded Atropatene (Azerbaijan) and destroyed the great Zoroastrian fire temple; in 627 he entered the Tigris provinces. Khosrow II attempted no resistance, and a revolution followed in which he was defeated and slain by his son Kavadh (Qobād) II (628). When Kavadh died a few months later, anarchy resulted. After a succession of short-time rulers, Yazdegerd III, grandson of Khosrow II, came to the throne in 632.

All these prolonged and exhausting hostilities drastically reduced the powers of both Byzantium and Iran. The door was open to a newly emerging force that challenged both states and religions—the Arabs. After several encounters, the fate of the Sāsānian empire was decided in the battle of Al-Qādisiyyah (636/637)—on one of the Euphrates canals, not far from Al-Ḥīrah—during which the Sāsānian commander in chief, Rostam, was killed. Ctesiphon with its treasures was at the mercy of the victors. Yazdegerd III fled to Media, where his generals tried to organize new resistance. The Battle of Nahāvand (642), south of Hamadān, put an end to their hopes. Yazdegerd sought refuge in one province after another, until at last, in 651, he was assassinated near Merv.

With the fall of the empire, the fate of its religion was also sealed. The Muslims officially tolerated the Zoroastrian faith, though persecutions were not unknown. Little by little it vanished from Iran, except for a few surviving adherents who remain to the present day in Yazd and a few other places. Other Zoroastrians emigrated to western India, where they are now chiefly concentrated in Mumbai (Bombay). These Parsi (Persians) have preserved only a relatively small portion of their sacred writings. They still number their years by the era of Yazdegerd III, the last king of their faith and the last Sāsānian sovereign of Iran.